National Semiconductor Launches Industry's First Full-Bridge PWM Controller with Integrated MOSFET Gate Drivers
Primary controller drives high-power modules in a small form factor

March 8, 2011 – National Semiconductor Korea (President: Choi Choong-won) today introduced the industry's first full-bridge PWM (Pulse Width Modulation) controllers that integrate all four primary-side bridge MOSFET gate drives. The LM5045 and LM5046 are well-suited for delivering high efficiency and power density in 4-brick and power 8-brick modules used in a variety of high-input voltage telecommunications infrastructure applications.

National will demonstrate the LM5045 and LM5046 products at Booth #202 at the Applied Power Electronics Conference and Expo (APEC), held March 6-10 in Fort Worth, Texas. APEC is one of the industry's leading conferences for power electronics professionals.
The LM5045 and LM5046 PWM controllers, part of National's energy-efficient PowerWise® family, enable full-bridge topology-based power converter designs to be easily implemented in small form factor power supplies by significantly reducing the external power components required for traditional full-bridge solutions. A demonstration of a transition phase full-bridge using the LM5046 can be found at http://bit.ly/LM5045video .

Technical Features of National's New Full-Bridge PWM Controller
The LM5045 PWM controller integrates all the features necessary to implement a conventional full-bridge topology power converter using either current-mode or voltage-mode control. For applications requiring zero-voltage switching (ZVS) to minimize electromagnetic interference (EMI) caused by conversion noise, the LM5046 PWM controller integrates all the features necessary to implement a phase-shifted full-bridge topology.

Available in thermally enhanced 5.0 mm x 5.0 mm x 0.8 mm LLP and compact 4.4 mm x 9.7 mm x 0.9 mm TSSOP packages, the full-bridge controllers operate on the primary side of isolated DC-DC converters with input voltages up to 100 V. These highly integrated controllers provide powerful 2 A high- and low-side gate drivers for the four external bridge MOSFETs, as well as control signals for the secondary-side synchronous rectifier MOSFETs and an internal high-voltage startup regulator. Intelligent startup of the synchronous rectifier (SR) allows monotonic turn-on of the power converter, even under pre-biased load conditions. The synchronous rectifier control signals provide independent, programmable leading/trailing dead time between the primary and auxiliary MOSFET control signals to optimize efficiency, and the SR signals are limited to 5 V for use with digital isolators. Additionally, it features dual-mode current overload protection with cycle-by-cycle current limiting and Hiccup mode restart, programmable